Metal carboxylate derivatives for use in synthetic materials, emulsions and suspensions

ABSTRACT

The invention relates to metal carboxylate derivatives of partially esterified α-olefin unsaturated polycarboxylic acid copolymers, the α-olefin containing 6 to 40 carbon atoms and the copolymer being esterified with an alcohol. At least 80 percent by weight of the unesterified copolymer has a molecular weight in the range from 1000 to 100,000. Preferably, the α-olefin is maleic anhydride and the alcohol contains 4 to 18 carbon atoms. The present compounds are surprisingly satisfactory internal and external lubricants for synthetic resin as PVC. Furthermore, the present compounds can be used as emulsifying and/or suspending agents, in particular when the alcohol is a polyethylene oxide glycol ether with 1 to 50 ethylene oxide units.

This is a continuation of application Ser. No. 795,176, filed 11/5/85,now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a metal carboxylate derivative of a partiallyesterified α-olefin-unsaturated polycarboxylic acid copolymer and to theuse of this compound as lubricant or stabilizer in synthetic materialsand as emulsifier and/or suspending agent.

2. Description of the Prior Art

A metal carboxylate derivative of the type indicated above is known fromU.S. Pat. No. 4,036,810, in which it is described as a stabilizer forchlorine-containing polymers. It is also mentioned as a lubricant forpolyvinyl chloride.

Apparently, however, a considerable proportion of the carboxylatesobtained by the process of said patent specification consist ofcompounds whose molecular weight is below 1000 and whose lubricatingaction is limited.

A metal carboxylate derivative of a partially esterifiedα-olefin-unsaturated polycarboxylic copolymer has now been found whichis a surprisingly satisfactory internal and external lubricant forsynthetic materials. This metal carboxylate derivative is characterizedin that at least 80 percent by weight of the unesterified copolymer hasa molecular weight in the range of from 1000 to 100,000.

It should be added that DE No. 2,727,329, DE No. 3,003,797 and DE No.3,136,931 describe partially and wholly esterified α-olefin-unsaturatedpolycarboxylic acid copolymers, more particularly α-olefin-maleic acidcopolymers suitable for use as lubricants. The present lubricantsdistinguish themselves from these copolymers by the presence of metalcarboxylate groups, which results in a surprisingly satisfactorylubricating or stabilizing action. Reference is also made to EP No.54,761, which claims a lubricant consisting of the salt of a copolymerof an α-β-ethylenically unsaturated acid and ethylene.

The invention also relates to the use of the present compounds asemulsifying and/or suspending agents and they are surprisingly effectiveas such. For instance, aqueous suspensions of clay can be moresatisfactorily stabilized with these compounds than with carboxy methylcellulose or copolymers from DE No. 3 136 931.

DETAILED DESCRIPTION OF THE INVENTION

As far as the metal carboxylate according to the invention is concerned,at least 80 percent by weight of the unesterified copolyester used inthe preparation has a molecular weight in the range of from 1000 to100,000. The average molecular weight is generally in the range of 1500to 50,000, preferably 2000 to 30,000. The molecular weight of thecopolymer is determined by gel permeation chromatography, as furtherdescribed in Example 1.

The α-olefin used for the preparation of the copolymer contains 6 to 40carbon atoms. It is preferred that the number of carbon atoms should bein the range of 10 to 24. Generally, the α-olefins used are mixtures oflargely linear aliphatic hydrocarbons. Alternatively, however, theα-olefin may be branched and contain one or more cycloaliphatic,aromatic, ether, halogen, nitro, cyano, hydroxy, alkoxy, carbonyl and/oracid groups. Examples of these α-olefins include: hexene-1, octene-1,decene-1, dodecene-1, tetradecene-1, hexadecene-1, octadecene-1,eicosene-1, docosene-1, tetracosene-1, hexacosene-1, octacosene-1,tricontene-1, dotricontene-1, tetratricontene-1, 7-methyldecene-2,vinylcyclohexane, cyclohexyl-hexadecene-1, 5-(2-norbornyl)-nonadecene-1,phenyldocosene-1, hexyl allyl ether, 9-chlorononene-1,5-methoxydecene-1, 8-ketotriadecene-1, 14-cyanopentadecene-1,10-undecene carboxylic acid and 15-n-hexadecene carboxylic acid.

The co-monomer of the α-olefin is a derivative of an unsaturatedpolycarboxylic acid, more particularly a derivative of cis- ortransethene dicarboxylic acid, such as a monoester of unsubstituted ormonosubstituted ethene dicarboxylic acid, a metal maleate, or maleicanhydride. Of course, also mixtures of these compounds may be used.Examples of unsaturated polycarboxylic acid derivatives include: maleicanhydride, 2-chloromaleic anhydride, 2-methylmaleic anhydride, dioctyltin maleate and the monomethyl, monobutyl, mono-2-ethylhexyl andmonomethyldiglycol ester of maleic acid, fumaric acid, 2-chloromaleicacid, citraconic acid, mesaconic acid, itaconic acid and aconitic acid.It is preferred that use should be made of maleic anhydride.

The partially esterified α-olefin-unsaturated polycarboxylic acidcopolymer is esterified with alcohols which may be linear, branched orcycloaliphatic and may contain one or more unsaturated bonds, ethergroups, ester groups and/or aromatic groups. Alternatively, mixtures ofalcohols may be used. When the present compounds are used as lubricantsor stabilizers, the alcohol generally contains 1 to 40 carbon atoms,preferably 4 to 18 carbon atoms. When the present compounds are used asemulsifying and/or suspending agents, the alcohol is preferably apolyalkylene oxide glycol ether, more particularly a polyethylene oxideglycol ether with 1 to 50 ethylene oxide units, and more particularlywith 1 to 30 ethylene oxide units.

Examples of suitable alcohols include: butanol, 2-ethylhexanol, talcalcohol, octadecanol, guerbet alcohol, diglycolethylene methyl ether,polyethylene glycol methyl ether, allyl alcohol, nonyl-phenolethoxylate, benzyl alcohol.

The partially esterified α-olefin-unsaturated polycarboxylic acidcopolymers are preferably esterified with 0.5 to 1.5 equivalents ofalcohol, particularly with 0.8 to 1.2, and more particularly 1.0equivalent of alcohol. The present compounds may contain all kinds ofmetals, such as metals from the groups Ia, IIa, IIb, IIIa and IVa of thePeriodic System of the Elements. Particularly suitable for the presentlubricants are barium, cadmium, calcium, magnesium, lead, tin and zinc.Also suitable are combinations of different metals, such as barium andzinc, and magnesium and zinc. For application as emulsifying and/orsuspending agents use is preferably made of metals from the group Ia,particularly sodium or potassium.

In the preparation of the present metal carboxylate derivatives ofpartially esterified α-olefin-unsaturated polycarboxylic acid copolymersroughly three reaction steps may be distinguished, viz.copolymerization, esterification and formation of metal carboxylates.Copolymerization and esterification generally take place first. Thecopolymerization is carried out in the presence of a radical initiatorsuch as di-tert-butyl peroxide, benzoyl peroxide, dilauryl peroxide,dicumyl peroxide, tert. butyl hydroperoxide and/or cumyl hydroperoxide.

A process of the type indicated above is described in DE No. 2,727,329,DE No. 3,003,797 and DE No. 3,136,931.

The resulting polymers have a low oligomer content, which is in contrastto the products prepared in accordance with U.S. Pat. No. 4,036,810,which contain a large proportion of compounds, such as dimers andtrimers, of a molecular weight below 1000.

In the copolymerization the amount of the reactants is preferably sochosen that the molar ratio of the α-olefin to the polycarboxylic acidin the copolymer is in the range of 1:2 to 2:1. This can generally beachieved by choosing the ratio of the monomers to be used in thepolymerization between 1:2 and 4:1.

Generally the formation of the metal carboxylate takes place in the lastreaction stage by bringing the acid groups of the partially esterifiedα-olefin-unsaturated polycarboxylic acid copolymer into reaction with ametal oxide, a metal hydroxide and/or a metal carbonate. Depending onthe reaction conditions and the choice of the reactants free acid groupsmay remain in the ready product. This is for instance the case if thedegree of esterification of the polycarboxylic acid is low. Theviscosity of the reaction mixture will then readily become so high thatthe metal oxide, the metal hydroxide and/or the metal carbonate will beconverted only to a limited extent. To ensure the presence in the endproduct of a considerable proportion of metal it is preferred that theratio of metal carboxylate groups to acid groups should be higher than0.5, more particularly higher than 0.1, preferably higher than 10. Theend products may also contain more than one equivalent of metal oxide.

The invention also relates to the use of the present metal carboxylatesof partially esterified α-olefin unsaturated polycarboxylic acidcopolymers as lubricants or stabilizers for synthetic materials and asemulsifying agents and/or suspending agents. Examples of syntheticmaterials in which the metal carboxylates may be used include polyvinylchloride, chlorinated polyvinyl chloride, polymer compositionscontaining polyvinyl chloride, such as polyvinyl chloride-polyvinylacetate, copolymers formed from vinyl chloride and other monomers, suchas vinyl acetate, vinylidene chloride or acrylonitrile, and otherpolymers such as polyolefins, polystyrene and polyacrylates.

It is preferred that the present compounds should be used inchlorine-containing synthetic materials, more particularly polyvinylchloride. These chlorine-containing materials are processed at elevatedtemperature and pressure. To permit rapid processing under theseconditions while avoiding degradation of the polymer lubricants areadded. On the one hand they serve to prevent excessive sticking to hotparts of the processing equipment (external lubrication) and on theother to reduce friction between the polymer particles (internallubrication). Most lubricants either only display a good internal or agood external lubricating action, which necessitates the use oflubricant mixtures. The present metal carboxylates of partiallyesterified α-olefin unsaturated polycarboxylic copolymers distinguishthemselves by their excellent internal and external lubricating actionand also have an unexpectedly good stabilizing effect on the polymer.Because of their high effectiveness the amount in which the presentlubricants are to be used need only be small (usually less than 5, moreparticularly 0.1 to 2 parts per hundred), which has a favourable effecton the mechanical properties of the end product.

The excellent effectiveness as regards external lubrication manifestsitself for instance in the long period the polymer can be milled withoutsticking to the metal mill rolls. Very often there is not even questionof any excessive sticking for a long time after the stabilization periodof the polymer. These properties make it possible for the processingequipment to be cleaned without any problems. Moreover, the presentlubricants cause no or only very little "plating out" on the metalsurface of the equipment.

The excellent internal lubricating effect appears from the short gellingtimes as measured with a Brabender Plasticorder. By aging tests carriedout in an oven at elevated temperature the thermal stability of thepolymer composition can be determined. The present metal carboxylatederivatives of partially esterified α-olefin polycarboxylic acidcopolymers are generally waxy or liquid and very suitable to be used incombination with stabilizers and/or other additives such asantioxidants, pigments, plasticizers, fillers, etc. Suitable PVCstabilizers are metal-containing compounds such as calcium soaps, bariumsoaps and zinc soaps, organotin compounds and lead salts, and organiccostabilizers such as phosphites and β-diketones. It is very wellpossible to prepare such ready mixtures of the present metalcarboxylates and other additives as are adapted to the processing ofparticular synthetic materials.

When the present copolymers are to be used as emulsifying and/orsuspending agents, it is preferred that use should be made of thosecopolymers that are esterified with a polyethylene oxide glycol etherwith 1 to 50, more particularly 1 to 30 ethylene oxide units and whichcontain as metal sodium and/or potassium. These compounds are suitablefor many uses, such as the dispersion of, say, clay or pigments, thestabilization of lactices and as lubricating agents in high water basedfluids.

The invention will be further described in the following examples.

EXAMPLE 1 (Copolymerization of C₁₈ -α-olefin and maleic anhydride)

A flask containing C₁₈ -α-olefin (756 g, 3 moles) was flushed withnitrogen and heated to 200° C. Subsequently, 10 equal portions of maleicanhydride (in all 294 g, 3 moles) and ditert-butyl peroxide (in all 15ml) were added with stirring and at 30 minute intervals. After theaddition over the next 11/2 hours of 3 more portions of ditertbutylperoxide (in all 4.5 ml) the mixture was heated to 200° C. for another30 minutes, after which a small amount (about 15 g) of volatileconstituents was distilled off by means of a water jet pump. Byelementary analysis it was found that the ratio olefin:maleic acid was0.987. From a gel permeation chromatography analysis it appeared thatthe polymer had a broad molecular weight distribution and an averagemolecular weight of 2950, 92 percent of the product having a molecularweight in the range of from 1000 to 22,000. Yield 1045 g.

The copolymers described in Table I were prepared in the same manner.

The molecular weight of the unesterified copolymers was determined withthe aid of a gel permeation chromatograph equipped with a micro-styragelcolumn (Waters Associates, see firm bulletin A 143, June 1974) and adifferential refractometer. The mobile phase consisted oftetrahydrofuran. For molecular weights below and above 3000 use was madeof, respectively, polyethylene glycol and polystyrene calibratingmaterials. By the average molecular weight is to be understood themolecular weight at the main peak.

                                      TABLE I                                     __________________________________________________________________________    Preparation of α-olefin polycarboxylic acid copolymers                                                Preparation of half esters                                          ratio     perc. co-                                                mol. ratio α-olefin:                                                                    average                                                                            polymer                                                  reactants                                                                           reaction                                                                           MA units                                                                           molec-                                                                             with mol.  reaction                                      α-olefin:                                                                     temp.(2)                                                                           in co-                                                                             ular weight of  temp.                                Sample                                                                            α-olefin                                                                     MA(1) (°C.)                                                                       polymer                                                                            weight                                                                             10.sup.3 -10.sup.5                                                                 alcohol                                                                             (°C.)                         __________________________________________________________________________    I   C.sub.6                                                                            2      64  0.82 22600                                                                              87   talc  150                                  II  C.sub.14-16                                                                        1     200  1.0  2650 86   PEGME(3)                                                                            150                                  III C.sub.14-16                                                                        0.5   200  0.55 3050 91   talc  150                                  IV  C.sub.18                                                                           1     200  0.99 2950 92   talc  150                                  V   C.sub.20-24                                                                        1     200  1.31 3750 92   talc  150                                  VI  C.sub.29-24                                                                        1     160  --   9150 80   talc  150                                  VII C.sub.30                                                                           1     200  --   3000 89   methyl                                                                              70-120(4)                            __________________________________________________________________________     (1)Maleic anhydride                                                           (2)Reaction time 7 hours (sample I, 10,5 hours)                               (3)Polyethylene glycol methyl ether (molecular weight 350)                    (4)Temperature rises from 70° to 120° C.                   

EXAMPLE 2 (Preparation of the half ester from the C₁₈ -α-olefin maleicanhydride copolymer)

The copolymer of Example 1 (300 g, containing 0.864 moles of maleic acidunits) and talc alcohol (219 g, 0.864 moles) were stirred for 4 hours at150° C.

Table I mentions several half esters that were prepared in the same way.

EXAMPLE 3 (Preparation of a calcium carboxylate derivative from the halfester of a C₁₈ -α-olefin maleic anhydride copolymer)

The half ester from Example 2 (600 g, containing 1 mole of acid groups)and calcium hydroxide (37 g, 0.5 moles) were stirred for 1-5 hours at110°-150° C., the calcium hydroxide being quantitatively converted and aclear viscous melt being formed.

Table II mentions several metal carboxylates prepared in a similarmanner. Incomplete conversions of the metal oxide, metal hydroxide ormetal carbonate were quantified by successively filtering, washing,drying and weighing unconverted metal oxide, metal hydroxide or metalcarbonate.

                                      TABLE II                                    __________________________________________________________________________    Preparation of metal carboxylates                                                       Average             Percentage acid                                           molecular           groups converted                                          weight of    Metal  into metal car-                                 Sample                                                                            Copolymer                                                                           copolymer                                                                            Half ester                                                                          carboxylate                                                                          boxylate groups                                 __________________________________________________________________________    Ba-I                                                                              C.sub.6 /MA                                                                         22600  talc  Ba     33                                              Ba-II                                                                             C.sub.14-16 /MA                                                                     2650   PEGME.sup.1                                                                         Ba     100                                             Ca-II                                                                             C.sub.14-16 /MA                                                                     2650   talc  Ca     100                                             Ba-III                                                                            C.sub.14-16 /MA                                                                     3050   talc  Ba     100                                             Ba-IV                                                                             C.sub.18 /MA                                                                        2950   talc  Ba     85                                              Ca-IV                                                                             C.sub.18 /MA                                                                        2950   talc  Ca     100                                             Ba-V                                                                              C.sub.20-24 /MA                                                                     2750   talc  Ba     100                                             Pb-VI                                                                             C.sub.20-24 /MA                                                                     9150   talc  Pb     88                                              Ba-VII                                                                            C.sub.30 /MA                                                                        3000   methyl                                                                              Ba     61                                              __________________________________________________________________________     .sup.1 polyethylene glycol methyl ether (molecular weight 350)           

EXAMPLE 4 (Milling experiments)

In a dry blender the following compounds were pre-mixed for 1 minute:

    ______________________________________                                        S-PVC (K-70)         100    parts                                             dioctylphthalate     25     parts                                             lubricant            see Table III                                            stabilizer           see Table III                                            ______________________________________                                    

The resulting compositions were mixed on a two-roll mill at 180° C.

    ______________________________________                                        roll diameters        110 and 125 mm                                          slit width between the rolls                                                                        0.8 to 1 mm                                             roll speed            20 rpm                                                  ______________________________________                                    

After about 1 minute a plastic mass was formed which, depending on thelubricant used, did or did not readily stick to the roll or did notstick to it at all (end of lubricating action). The results are given inTable III. They clearly show that the present lubricants are moreeffective than the commercially available lubricants: E-Wachs, Loxiol G70 and Loxiol G 71.

Also the plating out of samples with the present lubricants is far lessconsiderable, and the rolling skin did not stick to the roll for a longtime after the end of the stabilization period.

                  TABLE III                                                       ______________________________________                                                       Parts of Duration of                                                          lubricant                                                                              lubricant                                             Lubricant      (min)    action                                                ______________________________________                                        Ba-I           0.5      >>90                                                  Ba-II          0.5      35                                                    Ba-III         0.5      55                                                    Ba-IV          0.5      >70                                                   Ba-IV*         2.0      >>120                                                 Ba-V           0.5      30                                                    Ba-V           2.0      60                                                    Ba-VII         0.5      >160                                                  E-Wachs*       0.5      0                                                     Loxiol G 70*   0.5      10                                                    Loxiol G 71**  0.5      18                                                    ______________________________________                                         *stabilized with 2.5 parts of dibutyltin dimonomethyl maleate                 **stabilized with 2 parts of commercially available Ba--Zn stabilizer    

EXAMPLE 5 (Brabender experiments)

In a dry blender the following compounds were pre-mixed for 1 minute:

    ______________________________________                                        S-PVC (K-70)          100    parts                                            PbSO.sub.4 -4PbO      1.5    parts                                            Pb(C.sub.1 H.sub.35 COO).sub.2 2PbO                                                                 1      part                                             lubricant             see Table IV                                            ______________________________________                                    

An amount of 31 g of this mixture was tested in a Brabender at 25 rpmand at a temperature of 180° C.

The gelling times are mentioned in the table below.

                  TABLE IV                                                        ______________________________________                                                       Parts of Gelling time                                          Lubricant      lubricants                                                                             (min)                                                 ______________________________________                                        Pb-VI          0.5      1.5                                                                  1.0      3.0                                                                  1.5      7.1                                                   talc           0.5      2.5                                                   alcohol        1.0      3.9                                                                  1.5      9.3                                                   ______________________________________                                    

EXAMPLE 6 (Preparation of barium carboxylate and calcium carboxylatelubricants in accordance with U.S. Pat. No. 4,036,810)

In an autoclave a mixture of C₁₈ -α-olefin (504 g, 2 moles) and maleicanhydride (98 g, 1 mole) was stirred for 44 hours at 185° C.Subsequently, 233 g (0.93 moles) of the C₁₈ -α-olefin product weredistilled off from the crude product mixture. The main product was theadduct of one molecule of α-olefin and one molecule of maleic anhydrideand the residue contained 23 percent by weight of polymer of a molecularweight higher than 1000. In the way indicated in Example 2 the productmixture was converted with a talc alcohol into a half ester. The acidgroups of the half ester were subsequently reacted with barium oxide orcalcium oxide to be completely converted into the correspondingcarboxylates (see Example 3).

EXAMPLE 7 (Milling experiments)

In the way described in Example 4 milling experiments were carried outwith the following formulations:

    ______________________________________                                        S-PVC (K-70)         100    parts                                             dioctylphthalate     25     parts                                             lubricant            1.5    parts                                             ______________________________________                                    

The results mentioned in Table V demonstrate that the present lubricantsdisplay a far better external lubricating action than correspondingcompounds from U.S. Pat. No. 4,036,810 (see Example 6).

                  TABLE V                                                         ______________________________________                                                      Duration of                                                                   lubricating action                                              Lubricant     (min)                                                           ______________________________________                                        Ba-IV         >>120                                                           Ba-Example 6  25                                                              ______________________________________                                    

EXAMPLE 8 (Brabender experiments)

In the way described in Example 5 Brabender experiments were conductedwith the following formulations:

    ______________________________________                                        S-PVC (K-68)            100    parts                                          PbSO.sub.4 --4PbO       1.5    parts                                          Pb(C.sub.18 H.sub.36 O.sub.2).sub.2 2PbO                                                              1      part                                           paraffin (melting point 60° C.)                                                                0.6    parts                                          lubricant to be tested  0.6    parts                                          ______________________________________                                    

The results mentioned in Table VI show that the present lubricantsdisplay a far better internal lubricating action than correspondingcompounds from U.S. Pat. No. 4,036,810 (see Example 6).

                  TABLE VI                                                        ______________________________________                                                       Gelling time                                                   Lubricant      (min)                                                          ______________________________________                                        Ca-II          1.8                                                            Ba-IV          6.2                                                            Ca-IV          2.1                                                            Ba-Example 6   10.0                                                           Ca-Example 6   16.5                                                           ______________________________________                                    

EXAMPLE 9 (Milling experiments)

In the way described in Example 4 milling experiments were carried outwith the following formulations:

    ______________________________________                                        S-PVC (K-70)           100    parts                                           dioctylphthalate       2.5    parts                                           Ca/Zn-stabilizer (M330)                                                                              1.2    parts                                           lubricant to be tested 0.3    parts                                           ______________________________________                                    

The following lubricants were tested: Mg-IV, Ba-IV, half ester-IV,ester-IV (the two last-mentioned compounds are the copolymers IVaccording to DE No. 2,727,329 and DE No. 3,003,797, respectively halfand wholly esterified with talc alcohol).

The results given in Table VII illustrate that the present lubricantsdisplay a far better external lubricating action than the corresponding(half) ester copolymers.

                  TABLE VII                                                       ______________________________________                                                      Duration of lu-                                                               bricating action                                                Lubricant     (min)                                                           ______________________________________                                        Mg-IV         >45                                                             Ba-IV         >40                                                             half ester-IV 20                                                              ester-IV      20                                                              ______________________________________                                    

EXAMPLE 10 (Brabender tests)

In the way described in Example 5 Brabender tests were carried out withthe following formulations:

    ______________________________________                                        S-PVC (K-70)          100    parts                                            Ca/Zn-stabilizer      1.2    parts                                            lubricant to be tested                                                                              0.6    parts                                            ______________________________________                                    

The lubricants mentioned in Example 9 were tested. The gelling times aregiven in Table VIII. The results show that the present lubricantsdisplay a far better internal lubricating action than the (half) estersfrom DE No. 2,727,329 and DE No. 3,003,797.

                  TABLE VIII                                                      ______________________________________                                                       Gelling                                                        Lubricant      time (min)                                                     ______________________________________                                        Mg-IV          2.4                                                            Ba-IV          2.9                                                            half ester-IV  4.6                                                            ester-IV       17.5                                                           ______________________________________                                    

EXAMPLE 11 (Oven aging)

In a dry blender the following compounds were pre-mixed:

    ______________________________________                                        S-PVC (K-64)          100    parts                                            dioctylphthalate      25     parts                                            epoxidized soybean oil                                                                              3      parts                                            Ba/Zn-stabilizer      2      parts                                            ______________________________________                                    

Three compositions were prepared, each containing a different amount ofbarium toluate or Ba-VIII (which is identical with Ba-II except that itis esterified with talc alcohol). See Table IX. The compositions A, Band C were mixed on a mill for 5 minutes at 172° C. and subsequentlyaged in a Werner Mathis oven at 185° C. until degradation of the PVCtook place (recognizable by rapid discoloration).

All three compositions have the same metal content (0.17% Ba and 0.05%Zn).

The experiments show that PVC with the same metal content is betterstabilized when use is made of the present metal carboxylates.

                  TABLE IX                                                        ______________________________________                                                 Ba-o-toluate                                                                              Ba-VIII   Stabilization time                             Composition                                                                            (parts)     (parts)   (min)                                          ______________________________________                                        A        0.50        --        72                                             B        0.45        0.16      87                                             C        0.40        0.31      93                                             ______________________________________                                    

EXAMPLE 12 (Use as suspending agent)

A copolymer built up from equivalent amounts of maleic anhydride andC₁₂₋₁₄ -α-olefin and having a molecular weight of 20,000 was convertedwith polyethylene oxide glycol methyl ether (6-10 ethylene oxide units)into a half ester. The half ester (400 parts) readily dissolved in asolution of 14 parts of sodium hydroxide (100%) in water (586 parts).With the resulting sodium carboxylate derivative a suspension of clay inwater was prepared by stirring the components for 10 minutes (stirringspeed 100 rpm). The suspension was kept in a 100 ml-graduated cylinderfor 24 hours at room temperature, after which 10 ml of the suspensionwas pipetted from the graduated cylinder at half height. After the waterhad been evaporated off at 105° C., the amount of suspended clay wasdetermined by weighing. In reference experiments carboxymethyl celluloseand the half ester that had not been converted into a metal salt wereused as suspending agents. The results in Table X illustrate thefavourable suspending properties of the sodium carboxylate.

                  TABLE X                                                         ______________________________________                                                               % solid matter in                                      Suspension             suspension*                                            ______________________________________                                        5% clay                 0                                                     5% clay + 0.1% sodium carboxylate                                                                    35                                                     5% clay + 0.1% half ester                                                                            25                                                     5% clay + 0.1% carboxymethyl cellulose                                                               20                                                     ______________________________________                                         *based on amount weighed before evaporation                              

EXAMPLE 13 (Emulsion polymerization)

A 40%-dispersion of ethylene acrylate homopolymer in water was preparedby emulsion polymerization (initiator: potassium sulphate;polymerization temperature: 75° C.). Elfan® OS 46 (sodium olefinsulphate) was used as the emulsifying agent in different amounts. In oneexperiment it was partly replaced with the potassium salt of the halfester copolymer mentioned in Example 12 (see Table XI). The variousdispersions were mixed in a Star Mixer (which is similar to a Warringblender) for 2 minutes at 7500 rpm and subsequently filtered using an0.2 mm stainless steel screen. The coagulate was dried at 110° C. andweighed.

The results show the excellent mechanical stability of the dispersionswhen using potassium carboxylate.

                  TABLE XI                                                        ______________________________________                                        % stabillzer based on                                                         the polymer       mechanical stability                                        Elfan       potassium of the dispersion                                       OS 46       carboxylate                                                                             (% coagulate)                                           ______________________________________                                        2                     17                                                      4.5                   10                                                      2           2.5       0.1                                                     ______________________________________                                    

We claim:
 1. A metal carboxylate of a partially esterified α-olefinunsaturated polycarboxylic acid copolymer, the α-olefin containing 6 to40 carbon atoms and the copolymer being esterified with an alcohol,characterized in that one or more metals of said carboxylate areselected from group Ia of the Periodic Table of Elements, the ratio ofthe α-olefin to polycarboxylic units in the copolymer being in the rangeof from 1:2 to 2:1 and wherein at least 80 percent by weight of theunesterified copolymer has a molecular weight in the range of from 1000to 100,000.
 2. A metal carboxylate according to claim 1, characterizedin that it is a derivative of a partially esterified α-olefin-ethylenedicarboxylic acid copolymer.
 3. A metal carboxylate according to claim1, characterized in that the copolymer is formed from an α-olefin andmaleic anhydride.
 4. A metal carboxylate according to claim 1,characterized in that the unesterified copolymer has an averagemolecular weight in the range of from 2000 to 30,000.
 5. A metalcarboxylate according to claim 1, characterized in that the α-olefincontains 10 to 24 carbon atoms.
 6. A metal carboxylate according toclaim 1, characterized in that the alcohol contains 1 to 40 carbonatoms.
 7. A metal carboxylate according to claim 6, characterized inthat the alcohol contains 4-18 carbon atoms.
 8. A metal carboxylateaccording to claim 1, characterized in that the alcohol is apolyethylene oxide glycol ether with 1 to 50 ethylene oxide units.
 9. Ametal carboxylate according to claim 8, characterized in that thealcohol is a polyethylene oxide glycol ether with 1 to 30 ethylene oxideunits.
 10. A metal carboxylate according to claim 1, characterized inthat the polycarboxylic acid units in the copolymer are esterified with0.5 to 1.5 equivalents of alcohol.
 11. A metal carboxylate according toclaim 1, characterized in that the derivative contains one or moremetals selected from the group consisting of barium, cadmium, calcium,magnesium, lead, tin and zinc.
 12. A metal carboxylate according toclaim 1, characterized in that the derivative contains sodium and/orpotassium.
 13. A metal carboxylate according to claim 1, characterizedin that polycarboxylic acid units in the copolymer are esterified with0.8 to 1.2 equivalents of alcohol.